Since a bogie is an important component of a whole railway car, research in dynamic performance of a bogie is always the striving direction for those skilled in the art.
FIG. 1 is a partial three dimensional view of a bogie with a constant contact damper in the prior art. FIG. 2 is another partial three dimensional view of the bogie with the constant contact damper in the prior art. FIG. 3 is a partial side view of the bogie with the constant contact damper in the prior art. Referring to FIG. 1, FIG. 2 and FIG. 3, the bogie in the prior art comprises a bolster 11, two side frames 12 and four constant contact dampers. Two sides of two ends of the bolster 11 are respectively provided with a wedge pocket 111. A load spring 14 does not penetrate through a bottom plate 1111 of the wedge pocket 111. Each constant contact damper comprises a wedge 131, a damping spring 132, a side frame column wear plate 133 and a bolster inclined plane wear plate 134. The wedge 131 is a groove body, and is arranged in the wedge pocket 111 and latched on the bottom plate 1111. The damping spring 132 is arranged in the groove body with one end bearing against the top inner surface of the groove body and the other end bearing against the bottom plate 1111 in a compression state. The side frame column wear plate 133 is arranged on the side frame 12 and bears against the vertical plane of the wedge 131. The bolster inclined plane wear plate 134 is arranged in the wedge pocket 111 of the bolster 11 and bears against the inclined plane of the wedge 131.
When the car is running, the load spring 14 is compressed and generates spring bearing force along with the up and down vibration of the bolster 11 due to the gravitation of the empty car or loaded car. The friction damper can convert the vertical support force of the damper spring 132 to a horizontal lateral pressure on the side frame 12 and an inclined plane lateral pressure on the wedge pocket 111 from the wedge 131, causing a friction between the vertical plane of the wedge 131 and the side frame column wear plate 133, as well as a friction between the inclined plane of the wedge 131 and the bolster inclined plane wear plate 134 to generate damping forces. A relative friction coefficient of the friction damper can be obtained by the ratio between the damping forces and the support force of the spring. Those skilled in the art commonly appreciate that the relative friction coefficient is an important parameter for the damping effect implemented by the constant contact damper. Thereby, keeping the relative friction coefficient in an ideal numerical range whether the car is empty or loaded is a research goal.
Based what is described above, the inventor found in a long-term practice of the art that though the anti-lozenge deformation rigidity of the bogie is guaranteed with the aid of the large lateral dimension of the inclined plane of the wedge 131 along the car, the deformation of the damping spring 132 keeps constant whether the car is empty or loaded, which makes the damping force generated by the vertical support force of the damping spring 132 keep unchanged all the time, and eventually the relative friction coefficient can not be kept in an ideal numerical range when the car is empty and when the car is loaded, and thus the damping effect of the bogie is reduced.